1. Field of the Invention
The present invention relates to a floating carrier type transporting system for transporting small articles, and more particularly, to a floating carrier type transporting system which enables savings in energy and space.
2. Description of the Prior Art
In recent years, it has been common to transport slips, documents, cash, data, and others among a plurality of locations in a building by means of a transporting system as a part of office automation or factory automation.
For such purposes, in particular for a transporting system to be employed in clean rooms, the system is required to be one which is capable of moving articles to be transported quickly and quietly. For this reason, for a transporting system of this kind, there is often employed a method in which the carrier is supported on guide rails in noncontacting manner. Now, the use of pneumatic or magnetic means is in general use for noncontacting support of the carrier. Among other systems, the method of magnetically supporting the carrier may be considered to be the most promising supporting means in view of its superiority in the ability of following the guide rails and the noise reduction effect.
Now, the existing floating carrier type transporting system is one in which the carrier is supported stably by controlling the exciting current to the electromagnets. However, this has to lead to the drawback of consuming a large amount of power due to the necessity for constantly energizing the coils of the electromagnets. With this in mind, some systems have been proposed which attempt to reduce the power consumption by arranging to provide the majority of magnetomotive force required by the electromagnets by means of the permanent magnets. However, even in such a case, when an external force is applied sideways to the carrier due, for example, to its passing in a curved section of the guiding rails, there will be generated a rolling in the carrier. Since the carrier is being floated, however, convergence of the rolling motion in the carrier is poor, and the variations in the attractive forces of the permanent magnets have to be controlled by virtue of the attractive forces of the electromagnets. Any increase in the power consumption by the electromagnets in this situation is a matter of concern. Moreover, with the an increase in the power to be provided to the electromagnets because of the application of a lateral external force to the carrier, it becomes necessary to employ a power source with a large capacity as the power source for energizing the electromagnets, leading eventually to a system as a whole which has to be made large.